Measuring weight?
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Posts: 46,084
Any suggestions on a sensor i could use for a scale? i need to be
able to measure something like 1-5 lbs. thanks for any help. tom
able to measure something like 1-5 lbs. thanks for any help. tom
Comments
a potentiometer to the platform as it goes up and down? Something along the
lines of an envelope scale. You could attach a pot to the meter arm. Then
use the stamp to read the pots position.
Good luck.
At 04:10 PM 11/6/2000 -0000, you wrote:
>Any suggestions on a sensor i could use for a scale? i need to be
>able to measure something like 1-5 lbs. thanks for any help. tom
>
>
>
>
>
Sincerely
Kerry
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--So you think you need more memory... the LEM went to the moon on 16K,how
much do you REALLY need?
be "L", as it was compressed the inductance would change, which in turn
would cause a frequency shift of the L-C circuit. Calibrate the output
frequency to a few KNOWN weight values and create a mathematical
relationship within the Stamp/PIC.
A simple schmitt trigger (74HCT14) inverter oscillator fed into a
binary counter/divider (ECG4040B) should do the trick for getting
the frequency down to a manageable value.
Start off with a .001uF or .01uF Capacitor, experiment with different
outputs of the 4040B for best results.
L1
o----)))))---o
| |
| 1|\ 2 | 3 |\ 4
o----| \o----o----| \o----> to 4040B because frequency is to HIGH for
| |/ |/ a Stamp to process.
|
o----|(----> GND
C1
C1 = .001uF - .01uF
L1 = Coil / Spring
Note:
- place a .1uF Capacitor as close as possible across pins 7 & 14
of the 74HCT14 and the ECG 4040B
- Tie ALL unused pins (5,13,11, and 9) to GND or Vdd of the 74HCT14
>Tom: could you take a small platform, put a spring under it, and then attach
>a potentiometer to the platform as it goes up and down? Something along the
>lines of an envelope scale. You could attach a pot to the meter arm. Then
>use the stamp to read the pots position.
>Good luck.
>
>At 04:10 PM 11/6/2000 -0000, you wrote:
> >Any suggestions on a sensor i could use for a scale? i need to be
> >able to measure something like 1-5 lbs. thanks for any help. tom
> >
Beau Schwabe IC Mask Designer
National Semiconductor Network Products Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
1) Pressure transducers are often put into this type of service.
2) I have heard that antistatic foam changes resistance with weight applied.
I don't know how reliable, repeatable, etc. this is, but...
Regards,
Al Williams
AWC
*Floating point math for the Stamp, PIC, SX, or any microcontroller at
http://www.al-williams.com/awce/pak1.htm
Original Message
From: Al Williams [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=Fn2nbkD_VLO2bDjfePPdkLn63rAnROYuygNYe_Gzcm8SHJtHVoXS2DpfRGziqH8I90wTZB3qwtgV]alw@a...[/url
Sent: Monday, November 06, 2000 9:16 AM
To: basicstamps@egroups.com
Subject: RE: [noparse][[/noparse]basicstamps] Measuring weight?
How about using a strain gauge? You coud hook up two fixed resistors and
two strain gauges in a Wheatstone configuration. Epoxy the strain guages to
the bottom of the weighing platform and amplify the resultant differential
signal with an op amp. You could use the stamp to read the voltage. (use an
A/D converter to really get accurate). Set up a lookup table (weight versus
voltage) to determine the correct weight. There is a company called OMEGA
INSTRUMENTS on the web. They sell all kinds of strain gauges. You need the
postage stamp type. They are small gauges made from a plastic type material
with a small resistive element etched inside.
Just a thought,
Good luck
Jon Enoch
Do you want to use the stamp for the scale? a simply answer would be to
purchase a cheap digital household scale, they sell in NZ$ from $95, up pay
about $200 and you get a serial output. The scales are not for trade,
depending on the capacity will weigh by 2gram increments.Instead of trying
to make a simple loadcell maybe over in US you could purchase a non trade
loadcell which would be already calibrated about $20. I have never tried to
use one on a stamp.Trade quality loadcells here are from $195 each.I have
spent a life time making scales starting from mechanical up to modern
digital, from 2kg to 60 ton.Scale firms usually have a pile of junk
scales(like me) if there is one in your vicinity they would probably give
you one out of a obsolete scale,if you get one you would have to know the
output which is usually 1.5 to 3 mV.
Regards
Bernie Byers
Original Message
From: <tjwalton@u...>
To: <basicstamps@egroups.com>
Sent: Tuesday, November 07, 2000 5:10 AM
Subject: [noparse][[/noparse]basicstamps] Measuring weight?
> Any suggestions on a sensor i could use for a scale? i need to be
> able to measure something like 1-5 lbs. thanks for any help. tom
>
>
>
>
>
cell,multiple strain gages are connected to create the four legs for a
Wheatstone-bridge configuration.For a 10V bridge excitation with a rating of
2mV/V,20mV of signal will be available at full scale loading.
So a precision load cell amplifier is needed.
Regards
Mohamed Refky
>From: tjwalton@u...
>Reply-To: basicstamps@egroups.com
>To: basicstamps@egroups.com
>Subject: [noparse][[/noparse]basicstamps] Measuring weight?
>Date: Mon, 06 Nov 2000 16:10:59 -0000
>
>Any suggestions on a sensor i could use for a scale? i need to be
>able to measure something like 1-5 lbs. thanks for any help. tom
>
>
>
>
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I am interested with your idea. However, there
are a few doubts that I would to ask you.
(1)Where should I put the small platform?
(2)L1=coil/spring means I can use spring instead
of coil. Am I misinterpreted?
L1
o----)))))---o
| |
| 1|\ 2 | 3 |\ 4
o----| \o----o----| \o----> to 4040B because
| |/ |/ a Stamp to process.
|
o----|(----> GND
C1
C1 = .001uF - .01uF
L1 = Coil / Spring
---Beau Schwabe <bschwabe@a...> wrote:
>
> You could also set up the spring in an L-C oscillator. The spring
would
> be "L", as it was compressed the inductance would change, which in
turn
> would cause a frequency shift of the L-C circuit. Calibrate the
output
> frequency to a few KNOWN weight values and create a mathematical
> relationship within the Stamp/PIC.
>
> A simple schmitt trigger (74HCT14) inverter oscillator fed into a
> binary counter/divider (ECG4040B) should do the trick for getting
> the frequency down to a manageable value.
>
> Start off with a .001uF or .01uF Capacitor, experiment with different
> outputs of the 4040B for best results.
>
> L1
> o----)))))---o
> | |
> | 1|\ 2 | 3 |\ 4
> o----| \o----o----| \o----> to 4040B because frequency is to HIGH for
> | |/ |/ a Stamp to process.
> |
> o----|(----> GND
> C1
>
> C1 = .001uF - .01uF
> L1 = Coil / Spring
>
> Note:
> - place a .1uF Capacitor as close as possible across pins 7 & 14
> of the 74HCT14 and the ECG 4040B
>
> - Tie ALL unused pins (5,13,11, and 9) to GND or Vdd of the 74HCT14
>
>
>
> >Tom: could you take a small platform, put a spring under it, and
then attach
> >a potentiometer to the platform as it goes up and down? Something
along the
> >lines of an envelope scale. You could attach a pot to the meter
arm. Then
> >use the stamp to read the pots position.
> >Good luck.
> >
> >At 04:10 PM 11/6/2000 -0000, you wrote:
> > >Any suggestions on a sensor i could use for a scale? i need to be
> > >able to measure something like 1-5 lbs. thanks for any help. tom
> > >
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Network Products Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
>
>
>
>
>
>
>
>
>
>
_________________________________________________________
DO YOU YAHOO!?
̵
I am interested with your idea. However, there
are a few doubts that I would to ask you.
(1)Where should I put the small platform?
(2)L1=coil/spring means I can use spring instead
of coil. Am I misinterpreted?
Thousand thanks!
L1
o----)))))---o
| |
| 1|\ 2 | 3 |\ 4
o----| \o----o----| \o----> to 4040B because
| |/ |/ a Stamp to process.
|
o----|(----> GND
C1
C1 = .001uF - .01uF
L1 = Coil / Spring
---Beau Schwabe <bschwabe@a...> wrote:
>
> You could also set up the spring in an L-C oscillator. The spring
would
> be "L", as it was compressed the inductance would change, which in
turn
> would cause a frequency shift of the L-C circuit. Calibrate the
output
> frequency to a few KNOWN weight values and create a mathematical
> relationship within the Stamp/PIC.
>
> A simple schmitt trigger (74HCT14) inverter oscillator fed into a
> binary counter/divider (ECG4040B) should do the trick for getting
> the frequency down to a manageable value.
>
> Start off with a .001uF or .01uF Capacitor, experiment with different
> outputs of the 4040B for best results.
>
> L1
> o----)))))---o
> | |
> | 1|\ 2 | 3 |\ 4
> o----| \o----o----| \o----> to 4040B because frequency is to HIGH for
> | |/ |/ a Stamp to process.
> |
> o----|(----> GND
> C1
>
> C1 = .001uF - .01uF
> L1 = Coil / Spring
>
> Note:
> - place a .1uF Capacitor as close as possible across pins 7 & 14
> of the 74HCT14 and the ECG 4040B
>
> - Tie ALL unused pins (5,13,11, and 9) to GND or Vdd of the 74HCT14
>
>
>
> >Tom: could you take a small platform, put a spring under it, and
then attach
> >a potentiometer to the platform as it goes up and down? Something
along the
> >lines of an envelope scale. You could attach a pot to the meter
arm. Then
> >use the stamp to read the pots position.
> >Good luck.
> >
> >At 04:10 PM 11/6/2000 -0000, you wrote:
> > >Any suggestions on a sensor i could use for a scale? i need to be
> > >able to measure something like 1-5 lbs. thanks for any help. tom
> > >
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Network Products Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
>
>
>
>
>
>
>
>
>
>
_________________________________________________________
DO YOU YAHOO!?
̵
--- In basicstamps@egroups.com, tjwalton@u... wrote:
> Any suggestions on a sensor i could use for a scale? i need to be
> able to measure something like 1-5 lbs. thanks for any help. tom
>Hello Beau Schwabe
>
> I am interested with your idea. However, there
>are a few doubts that I would to ask you.
> (1)Where should I put the small platform?
> (2)L1=coil/spring means I can use spring instead
> of coil. Am I misinterpreted?
No, you are correct. The spring IS the coil (as long as the
"spring-windings" don't collapse and touch one another.
Placing the platform is up to you...
Note: if you use a metal plate or tray to place items in to
be weighed, make sure there is no electrical connection
between the "spring" and the plate, and that the plate
is connected to an electrical ground. (GND or Vdd)
>
> L1
> o----)))))---o
> | |
> | 1|\ 2 | 3 |\ 4
> o----| \o----o----| \o----> to 4040B because
> | |/ |/ a Stamp to process.
> |
> o----|(----> GND
> C1
>
> C1 = .001uF - .01uF
> L1 = Coil / Spring
>
Beau Schwabe IC Mask Designer
National Semiconductor Network Products Division
500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
balance. The idea was to use a regular analog meter on its side. You sensed
when the needle was at mid point and figured how much current you had to
supply to get the needle to the middle. Of course, that would be good only
for a few grams, but I thought it was a neat idea.
Al Williams
AWC
* Stamp FAQ: http://www.al-williams.com/wd5gnr/stampfaq.htm
>
Original Message
> From: Beau Schwabe [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=xUQ45JCn7qWQU6vMUBjVOWvPaVzH-ZaxIk7pTokcUznZ-_0ds4szJqxbPfWTZoCilVI9bkXUoIqCL_90I0GuUEcZOA]bschwabe@a...[/url
> Sent: Tuesday, November 07, 2000 9:58 AM
> To: basicstamps@egroups.com
> Subject: Re: [noparse][[/noparse]basicstamps] Measuring weight?
>
>
> At 01:31 PM 11/7/00 +0900, you wrote:
> >Hello Beau Schwabe
> >
> > I am interested with your idea. However, there
> >are a few doubts that I would to ask you.
> > (1)Where should I put the small platform?
> > (2)L1=coil/spring means I can use spring instead
> > of coil. Am I misinterpreted?
>
> No, you are correct. The spring IS the coil (as long as the
> "spring-windings" don't collapse and touch one another.
>
> Placing the platform is up to you...
>
> Note: if you use a metal plate or tray to place items in to
> be weighed, make sure there is no electrical connection
> between the "spring" and the plate, and that the plate
> is connected to an electrical ground. (GND or Vdd)
>
>
> >
> > L1
> > o----)))))---o
> > | |
> > | 1|\ 2 | 3 |\ 4
> > o----| \o----o----| \o----> to 4040B because
> > | |/ |/ a Stamp to process.
> > |
> > o----|(----> GND
> > C1
> >
> > C1 = .001uF - .01uF
> > L1 = Coil / Spring
> >
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Network Products Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
>
>
>
>
>
>
>
>
Thank you very much. I will
try it. I am not sure whether
I got the exact picuture of what you
mean. Anyway, I will try it.
Thank you.
Sze Keat
---Beau Schwabe <bschwabe@a...> wrote:
>
> At 01:31 PM 11/7/00 +0900, you wrote:
> >Hello Beau Schwabe
> >
> > I am interested with your idea. However, there
> >are a few doubts that I would to ask you.
> > (1)Where should I put the small platform?
> > (2)L1=coil/spring means I can use spring instead
> > of coil. Am I misinterpreted?
>
> No, you are correct. The spring IS the coil (as long as the
> "spring-windings" don't collapse and touch one another.
>
> Placing the platform is up to you...
>
> Note: if you use a metal plate or tray to place items in to
> be weighed, make sure there is no electrical connection
> between the "spring" and the plate, and that the plate
> is connected to an electrical ground. (GND or Vdd)
>
>
> >
> > L1
> > o----)))))---o
> > | |
> > | 1|\ 2 | 3 |\ 4
> > o----| \o----o----| \o----> to 4040B because
> > | |/ |/ a Stamp to process.
> > |
> > o----|(----> GND
> > C1
> >
> > C1 = .001uF - .01uF
> > L1 = Coil / Spring
> >
>
>
>
>
> Beau Schwabe IC Mask Designer
> National Semiconductor Network Products Division
> 500 Pinnacle Court, Suite 525 Mail Stop GA1 Norcross, GA 30071
>
>
>
>
>
>
>
>
>
>
>
_________________________________________________________
DO YOU YAHOO!?
̵
for a sensor on the front of a fork lift, to tell the driver his load was to
heavy, prevents fork lift tipping over, I've lost contact with this old mate
of mine, but looking at the spec's for these gauges I would think it would
be very easy to set up.
John.
Original Message
From: <tjwalton@u...>
To: <basicstamps@egroups.com>
Sent: Tuesday, November 07, 2000 3:14 PM
Subject: [noparse][[/noparse]basicstamps] Re: Measuring weight?
> Thanks, everyone, for the great ideas! tom
>
>
> --- In basicstamps@egroups.com, tjwalton@u... wrote:
> > Any suggestions on a sensor i could use for a scale? i need to be
> > able to measure something like 1-5 lbs. thanks for any help. tom
>
>
>
>
>
an outfit called K-tron (I think) and they had a very interesting way to
measure the weight on a scale. They had a flex beam that was surrounded by
a coil that had a high frequency (somewhere around 50Khz or so, can't
remember) fed to it. As the beam moved in the coil, it changed the resonant
frequency of the coil. Measure the change in frequency, know the weight.
The accuracy was absolutely astounding and the idea very simple. No time
required for coming up to temperature like the usual load cell, just turn it
on and weigh.
I think the company is doing other things now, but it one other option
to consider if you wanted to home-brew one.
your requirments.
alan
Original Message
From: <tjwalton@u...>
To: <basicstamps@egroups.com>
Sent: Monday, November 06, 2000 8:10 AM
Subject: [noparse][[/noparse]basicstamps] Measuring weight?
> Any suggestions on a sensor i could use for a scale? i need to be
> able to measure something like 1-5 lbs. thanks for any help. tom
>
>
>
>
lbf-200,000lbf if i can be of help let me know.
alan
Original Message
From: john & lisa <johnlisa@c...>
To: <basicstamps@egroups.com>
Sent: Tuesday, November 07, 2000 3:27 PM
Subject: Re: [noparse][[/noparse]basicstamps] Re: Measuring weight?
> Have you thought about a strain gauge, mate of mine used it a few years
back
> for a sensor on the front of a fork lift, to tell the driver his load was
to
> heavy, prevents fork lift tipping over, I've lost contact with this old
mate
> of mine, but looking at the spec's for these gauges I would think it would
> be very easy to set up.
> John.
>
Original Message
> From: <tjwalton@u...>
> To: <basicstamps@egroups.com>
> Sent: Tuesday, November 07, 2000 3:14 PM
> Subject: [noparse][[/noparse]basicstamps] Re: Measuring weight?
>
>
> > Thanks, everyone, for the great ideas! tom
> >
> >
> > --- In basicstamps@egroups.com, tjwalton@u... wrote:
> > > Any suggestions on a sensor i could use for a scale? i need to be
> > > able to measure something like 1-5 lbs. thanks for any help. tom
> >
> >
> >
> >
> >
>
>
>
>
It sounds interesting. Do you know
any site that have details information(
and photo).
Besides, can you tell me what is flex beam?
Just want to know wether I am misinterpret
or not.
You mean when any object(to be weighed)
is put onto a platform, this will cause
the beam moved into the coil, and this will
cause a change in frequency.Then we just
calculate the change of the frequency to
get the weigh.Am I correct?
Thank you.
Sze Keat
---carl mciver <cmciver@m...> wrote:
>
> I used to work as an industrial scale tech and worked on scales
made by
> an outfit called K-tron (I think) and they had a very interesting
way to
> measure the weight on a scale. They had a flex beam that was
surrounded by
> a coil that had a high frequency (somewhere around 50Khz or so, can't
> remember) fed to it. As the beam moved in the coil, it changed the
resonant
> frequency of the coil. Measure the change in frequency, know the
weight.
> The accuracy was absolutely astounding and the idea very simple. No
time
> required for coming up to temperature like the usual load cell, just
turn it
> on and weigh.
> I think the company is doing other things now, but it one other
option
> to consider if you wanted to home-brew one.
>
>
>
>
>
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